Organic electroluminescence device with silver alloy anode and method of manufacturing the same

ABSTRACT

Provided are an organic electroluminescence device capable of enhancing reflectance of an anode, thereby resulting in improved light-emitting efficiency and a method of manufacturing the same. An anode ( 12 ), a thin film layer for hole injection ( 13 ), an insulating layer ( 14 ), an organic layer ( 15 ) including a luminescent layer ( 15 C) and a cathode ( 16 ) including a semi-transparent electrode ( 16 A) are laminated in order on a substrate ( 11 ). The anode ( 12 ) comprises silver which is a metal with high reflectance or an alloy including silver, and the thin film layer for hole injection ( 13 ) comprises chromium oxide or the like. Light generated in the luminescent layer ( 15 C) is multiply reflected between the anode ( 12 ) and the semi-transparent electrode ( 16 A) to be emitted from the cathode ( 16 ). As the reflectance of the anode ( 12 ) is enhanced, the light generated in the luminescent layer ( 15 C) can be efficiently emitted. An alloy comprised in the anode ( 12 ) preferably includes silver, palladium and copper, and a silver content is preferably 50% by mass or over.

The subject matter of application Ser. No. 10/399,030, is incorporatedherein by reference. The present application is a continuation of U.S.Ser. No. 10/399,030, filed Apr. 11, 2003 now U.S. Pat. No. 7,285,905 ,which is a 371 U.S. National Stage filing of PCT application No.PCT/JP02/06354 filed Jun. 25, 2002, claims priority to Japanese PatentApplication No. JP2001-264410 filed Aug. 31, 2001. The presentapplication claims priority to these previously filed applications.

TECHNICAL FIELD

The present invention relates to an organic electroluminescence device(organic EL device) comprising one or more organic layers including aluminescent layer between an anode and a cathode, and emitting lightgenerated specifically in the luminescent layer, and a method ofmanufacturing the same.

BACKGROUND ART

In recent years, organic EL displays using an organicelectroluminescence device as an alternative to liquid crystal displayshave become a focus of attention. The organic EL displays are of aself-luminous type, so it is considered that the organic EL displayshave advantages of a wide viewing angle, low power consumption andadequate response to high-definition high-speed video signals.Therefore, the organic EL displays have been developed to achieve thepractical use thereof.

FIG. 6 shows a configuration of the organic electroluminescence device.The organic electroluminescence device comprises an anode 112, anorganic layer 115 including a hole injection layer 115A, a holetransport layer 115B and a luminescent layer 115C, and a cathode 116laminated in this order on a substrate 111. Although light generated inthe luminescent layer 115C may be emitted from the substrate 111, asshown in FIG. 6, the light may be emitted from the cathode 116.

When the light is emitted from the cathode 116, it is often the casethat the anode 112 comprises a metal such as chromium (Cr), and thecathode 116 comprises a transparent conductive material such as acompound of indium (In), tin (Sn) and oxygen (O) (ITO; indium tinoxide). The light generated in the luminescent layer 115C may bedirectly emitted through the cathode 116 as indicated by an arrow 117 inFIG. 6, and as indicated by an arrow 118, the light may be reflected onthe anode 112 once and then emitted through the cathode 116.

However, conventionally, the anode 112 comprises chromium or the like,so there is a problem that light absorptance by the anode 112 is high,thereby a loss of light emitted after reflected on the anode 112 islarge. The absorptance by the anode has a large influence on the organicelectroluminescence device. When light-emitting efficiency is low, theamount of current required to obtain the same intensity is increased. Anincrease in the amount of drive current affects on the life of thedevice, which is a critical problem in the practical use of the organicelectroluminescence device.

In view of the foregoing, it is an object to provide an organicelectroluminescence device capable of enhancing the reflectance of theanode so as to improve light-emitting efficiency, and a method ofmanufacturing the same.

DISCLOSURE OF THE INVENTION

An organic electroluminescence device according to the inventioncomprises one or more organic layers including a luminescent layerbetween an anode and a cathode, and emits light generated in theluminescent layer from the cathode, wherein the anode comprises silver(Ag) or an alloy including silver.

In a first method of manufacturing an organic electroluminescence deviceaccording to the invention, the organic electroluminescence comprisesone or more organic layers including a luminescent layer between ananode and a cathode and emits light generated in the luminescent layerfrom the cathode, and the method comprises the steps of: forming theanode comprising silver or an alloy including silver on a substrate;forming a thin film layer for hole injection made of a material with ahigher work function than that of the anode on the anode in anatmosphere of an inert gas; forming the one or more organic layersincluding the luminescent layer on the thin film layer for holeinjection; and forming the cathode on the organic layer. In a secondmethod of manufacturing an organic electroluminescence device accordingto the invention, the organic electroluminescence comprises one or moreorganic layers including a luminescent layer between an anode and acathode and emits light generated in the luminescent layer from thecathode, and the method comprises the steps of: forming the anodecomprising silver or an alloy including silver on a substrate; forming athin film layer for hole injection made of a material with a higher workfunction than that of the anode on the anode by use of an area mask withan aperture corresponding to an area where the thin film layer for holeinjection is intended to be formed; forming the one or more organiclayers including the luminescent layer on the thin film layer for holeinjection; and forming the cathode on the organic layer.

In the organic electroluminescence device according to the invention,the anode comprises silver with a highest reflectance of all of metalsor an alloy including silver, so a loss of light absorption by the anodeis reduced, thereby light generated in the luminescent layer can beefficiently emitted.

In the first method of manufacturing an organic electroluminescencedevice according to the invention, after the anode comprising silver oran alloy including silver is formed on the substrate, on the anode, thethin film layer for hole injection is formed in an atmosphere of aninert gas. Therefore, thin film layer for hole injection prevents theanode from being deteriorated, and the anode can be prevented from beingdeteriorated during the formation of the thin film layer for holeinjection.

In the second method of manufacturing an organic electroluminescencedevice according to the invention, after the anode comprising silver oran alloy including silver is formed on the substrate, the thin filmlayer for hole injection is formed on the anode by use of an area maskwith an aperture corresponding to an area where the thin film layer forhole injection is intended to be formed. Therefore, the thin film layerfor hole injection can prevent the anode from being deteriorated, andetching is not required to form the thin film layer for hole injection,so the anode can be prevented from being deteriorated and deformed dueto etching.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a configuration of an organicelectroluminescence device according to a first embodiment of theinvention;

FIGS. 2A through 2C are sectional views showing a method ofmanufacturing the organic electroluminescence device shown in FIG. 1 insequence;

FIGS. 3A and 3B are sectional views showing a modification of a methodof the organic electroluminescence device according to the firstembodiment in sequence;

FIG. 4 is a sectional view of a configuration of an organicelectroluminescence device according to a second embodiment of theinvention;

FIGS. 5A and 5B are sectional views showing a method of manufacturingthe organic electroluminescence device shown in FIG. 4 in sequence; and

FIG. 6 is a sectional view of a configuration of a conventional organicelectroluminescence device.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will be described in moredetail below referring to the accompanying drawings.

[First Embodiment]

FIG. 1 shows a sectional configuration of an organic electroluminescencedevice according to a first embodiment of the invention. An organicelectroluminescence device 10, which is used for an extra-thin typeorganic EL display or the like, comprises an anode 12, a thin film layerfor hole injection 13, an insulating layer 14, an organic layer 15 and acathode 16 which are laminated in this order on a substrate 11 made of,for example, an insulating material such as glass. Further, apassivation film (not shown) is formed on the cathode 16, and the wholedevice is sealed with a sealing substrate (not shown).

The anode 12 has a thickness in a laminating direction (hereinaftersimply referred to as thickness) of, for example, 200 nm, and comprisessilver or an alloy including silver, because silver, which has highestreflectance of all metals, can reduce a loss of light absorption by theanode 12. The anode 12 comprising silver is preferable because it canhave the highest reflectance, although the anode 12 comprising an alloyof silver and other metal is more preferable, because chemical stabilityand processing accuracy of the anode 12 can be enhanced, and theadhesion of the anode 12 to the substrate 11 and the thin film layer forhole injection 13 can be improved. Silver has very high reactivity, lowprocessing accuracy and low adhesion, thereby it is very difficult tohandle silver.

A silver content in the alloy is preferably 50% by mass or over, so thatthe reflectance of the anode 12 can be sufficiently enhanced. As thealloy including silver, for example, an alloy including silver,palladium (Pd) and copper (Cu) is preferable. A palladium content and acopper content in the alloy are preferably within a range, for example,from 0.3% by mass to 1% by mass, because the reflectance can besufficiently enhanced, and the processing accuracy, the chemicalstability and the adhesion can be enhanced.

The thin film layer for hole injection 13 is provided to enhanceefficiency of hole injection into the organic layer 15, and comprises amaterial with a higher work function than that of the anode 12.Moreover, the thin film layer for hole injection 13 has a function as aprotective film which prevents silver or the alloy including silver fromreacting with oxygen or a sulfur content in air, and mitigates damage tothe anode 12 in a manufacturing step after forming the anode 12.Materials of the thin film layer for hole injection 13 include, forexample, a metal such as chromium, nickel (Ni), cobalt (Co), molybdenum(Mo), platinum (Pt) or silicon (Si), an alloy including at least oneselected from the above metals, or an oxide of any one of the metals orthe alloy, a nitride of any one of the metals or the alloy, or atransparent conductive material such as ITO. It is preferable that thethickness of the thin film layer for hole injection 13 is determineddepending upon the light transmittance and electrical conductivity ofthe material. For example, when the thin film layer for hole injection13 comprises an oxide or a nitride with relatively low electricalconductivity such as chromium oxide (III) (Cr₂O₃), the thickness ispreferably as thin as, for example, approximately 5 nm. When the thinfilm layer for hole injection 13 comprises a metal with high electricalconductivity and low transmittance, the thickness is preferably as thinas, for example, a few nm. On the other hand, when the thin film layerfor hole injection 13 comprises ITO with high electrical conductivityand high transmittance, the thickness can be as thick as a few nm to afew tens nm.

The insulating layer 14 is provided to secure the insulation between theanode 12 and the cathode 16 and accurately form a light-emitting area inthe organic electroluminescence device 10 in a desired shape. Theinsulating layer 14 comprises an insulating material such as, forexample, silicon dioxide (SiO₃). The insulating layer 14 has a thicknessof, for example, approximately 600 nm, and in the insulating layer 14,an aperture portion 14A is disposed corresponding to a light-emittingarea.

The organic layer 15 includes a hole injection layer 15A, a holetransport layer 15B and a luminescent layer 15C, all of which are madeof an organic material, laminated in this order from the anode 12. Thehole injection layer 15A and the hole transport layer 15B are providedto enhance efficiency of hole injection into the luminescent layer 15C.The luminescent layer 15C emits light by current injection, and an areaof the luminescent layer 15C corresponding to the aperture portion 14Aof the insulating layer 14 emits light.

The hole injection layer 15A has a thickness of, for example,approximately 30 nm, and is made of4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (MTDATA). The holetransport layer 15B has a thickness of, for example, approximately 20nm, and is made of bis[(N-naphthyl)-N-phenyl]benzidine (α-NPD).

The luminescent layer 15C has a thickness of, for example, approximately50 nm, and is made of 8-quinolinol aluminum complex (Alq).

The cathode 16 includes a semi-transparent electrode 16A havingsemi-transparency to light generated in the luminescent layer 15C, and atransparent electrode 16B having transmittance for the light generatedin the luminescent layer 15C, which are laminated in this order from theorganic layer 15. The semi-transparent electrode 16A has a thickness of,for example, approximately 10 nm, and is made of an alloy of magnesium(Mg) and silver (MgAg alloy). The magnesium-silver alloy preferably hasa magnesium-to-silver mass ratio of 9 to 1.

The semi-transparent electrode 16A is provided to reflect the lightgenerated in the luminescent layer 15C between the semi-transparentelectrode 16A and the anode 12. In other words, the semi-transparentelectrode 16A and the anode 12 constitute a resonant portion in aresonator which resonates the light generated in the luminescent layer15C. It is preferable that such a resonator is constituted, because thelight generated in the luminescent layer 15C causes multipleinterference to function as a kind of narrow-band filter, and thereby ahalf-value width of a spectrum of emitted light can be reduced and colorpurity can be improved.

For that purpose, it is preferable to match a peak wavelength of thenarrow-band filter and a peak wavelength of the spectrum of lightdesired to be emitted. In other words, assuming that a phase shift ofreflected light generated in the anode 12 and the semi-transparentelectrode 16A is Φ (rad), an optical distance between the anode 12 andthe semi-transparent electrode 16A is L, and the peak wavelength of thespectrum of light desired to be emitted from the cathode 16 is λ, theoptical distance L preferably satisfies a mathematical formula 1, and infact, the optical distance L is preferably selected to be a positiveminimum value satisfying the mathematical formula 1. Further, in themathematical formula 1, the units of L and λ may be the same, forexample, “nm”.2L/λ+Φ/2π=q (q is an integer)   (Mathematical Formula 1)

The transparent electrode 16B is provided to reduce electricalresistance of the semi-transparent electrode 16A, and is made of anelectrically conductive material having sufficient translucency to thelight generated in the luminescent layer 15C. As the material of thetransparent electrode 16B, for example, a compound including indium,zinc (Zn) and oxygen is preferable, because the compound can obtain goodelectrical conductivity even if film formation is carried out at ambienttemperature. The transparent electrode 16B preferably has a thicknessof, for example, approximately 200 nm.

The organic electroluminescence device 10 can be manufactured accordingto the following steps, for example.

FIGS. 2A through 2C show a method of manufacturing the organicelectroluminescence device 10 in sequence. At first, as shown in FIG.2A, the anode 12 comprising silver or an alloy including silver with theabove-described thickness is formed on the substrate 11 made of theabove-described material through, for example, direct currentsputtering, which is carried out by the use of, for example, argon (Ar)as a sputtering gas at a pressure of, for example, 0.2 Pa and an outputof, for example, 300 W.

Next, as shown in FIG. 2A, the thin film layer for hole injection 13made of the above-described material with the above-described thicknessis formed on the anode 12 through, for example, high frequencysputtering. At this time, the thin film layer for hole injection 13 ispreferably formed at a pressure of, for example, 0.3 Pa and an outputof, for example, 10 W in an atmosphere of an inert gas using an inertgas of argon (Ar), nitrogen (N₂) or the like as a sputtering gas. Thereactivity of silver comprised in the anode 12 is high, so when the thinfilm layer for hole injection 13 is formed in an atmosphere of oxygen,the anode 12 is also oxidized. Therefore, the thin film layer for holeinjection 13 made of an oxide such as, for example, chromium oxide ispreferably formed not in an atmosphere of oxygen using a metal targetsuch as a chromium target but in an atmosphere of an inert gas-using anoxide target such as chromium oxide.

Next, as shown in FIG. 2B, the anode 12 and the thin film layer for holeinjection 13 are selectively etched through lithography by, for example,a mixed solution of nitric acid, phosphoric acid and acetic acid to bepatterned in predetermined shapes. After that, as shown in FIG. 2B, theinsulating layer 14 with the above-described thickness is formed allover the substrate 11 through CVD (chemical vapor deposition), and anarea of the insulating layer 14 corresponding to a light-emitting areais selectively removed through, for example, lithography to form theaperture portion 14A.

After forming the insulating layer 14, as shown in FIG. 2C, the holeinjection layer 15A, the hole transport layer 15B, the luminescent layer15C and the transparent electrode 16A all of which are made of theabove-described materials with the above-described thicknesses areformed in order through, for example, vapor deposition. At this time, bythe use of a metallic area mask 21 with an aperture 21A corresponding toan area where the layers are intended to be formed, the layers arepreferably formed corresponding to the light-emitting area, that is, theaperture portion 14A of the insulating layer 14. However, it isdifficult to carry out vapor deposition only on the aperture portion 14Awith high accuracy, so the layers are preferably formed on the wholeaperture portion 14A and an edge of the insulating layer 14 around theaperture portion 14A.

More specifically, at first, 0.2 g each of the materials of the holeinjection layer 15A, the hole transport layer 15B and the luminescentlayer 15C are filled in, for example, respective boats for resistanceheating, and the boats are mounted on predetermined electrodes of avacuum deposition apparatus (not shown). For example, regardingmagnesium and silver forming the semi-transparent electrode 16A, 0.1 gof magnesium and 0.4 g of silver are filled in respective boats forresistance heating, and the boats are mounted on predeterminedelectrodes of the vacuum deposition apparatus (not shown). Further, as acathode of the vacuum deposition apparatus (not shown), for example, analloy of magnesium and silver is used. Next, after an pressure of anatmosphere in the vacuum deposition apparatus (not shown) is reduced to,for example, 1.0×10⁻⁴ Pa, a voltage is applied to each boat forresistance heating to heat in order, thereby the hole injection layer15A, the hole transport layer 15B, the luminescent layer 15C and thesemi-transparent electrode 16A are deposited in order. When thesemi-transparent electrode 16A is deposited, magnesium and silver aredeposited together, and a growth rate ratio of magnesium to silver isset at, for example, 9:1.

Finally, the transparent electrode 16B is formed on the semi-transparentelectrode 16A by the use of the same metallic mask 21 through, forexample, direct current sputtering, which is carried out by the use of amixed gas of argon and oxygen (a volume ratio of Ar:O₂=1000:5) as asputtering gas at a pressure of, for example, 0.3 Pa, and an output of,for example, 40 W. Thereby, the organic electroluminescence device 10shown in FIG. 1 is formed.

In the organic electroluminescence device 10, when a predeterminedvoltage is applied between the anode 12 and the cathode 16, a current isinjected into the luminescent layer 15C to re-bond holes and electrons,thereby light is emitted mainly from an interface on a side of theluminescent layer 15C. The light is multiply reflected between the anode12 and the semi-transparent electrode 16A, and then passes through thecathode 16 to be emitted. In the embodiment, the anode 12 comprisessilver or an alloy including silver, so reflectance of the anode 12 isenhanced. Thereby, the light generated in the luminescent layer 15C isefficiently emitted.

Thus, according to the embodiment, the anode 12 comprises silver or analloy including silver, so the reflectance of the anode 12 can beenhanced, and a loss of light absorption by the anode 12 can be reduced.Thereby, efficiency of emitting the light generated in the luminescentlayer 15C can be improved.

More specifically, the anode 12 comprising an alloy including silver,palladium and copper allows improving the chemical stability, theprocessing accuracy and the adhesion. Further, when the silver contentin the alloy is 50% by mass or over, the reflectance can be sufficientlyenhanced, and the chemical stability, the processing accuracy and theadhesion can be improved.

Moreover, when the thin film layer for hole injection 13 made of amaterial with a higher work function than that of the anode 12 isdisposed between the anode 12 and the organic layer 15, the efficiencyof hole injection into the organic layer 15 can be further enhanced.Further, silver or an alloy including silver comprised in the anode 12can be prevented from reacting with oxygen or a sulfur content in air,and damage to the anode 12 in a manufacturing process after forming theanode 12 can be mitigated.

In addition, in the case where the thin film layer for hole injection 13is formed in an atmosphere of an inert gas, even if the anode 12comprises silver with high reactivity or an alloy including silver, theanode 12 can be prevented from being deteriorated such as oxidationduring the formation of the thin film layer for hole injection 13. Thus,target properties of the anode 12 can be obtained, and thereby theorganic electroluminescence device 10 according to the embodiment can beeasily obtained.

[Modification]

FIGS. 3A and 3B show a modification of a method of manufacturing theorganic electroluminescence device 10 according to the first embodiment.In the modification, the thin film layer for hole injection 13 is formedby the use of an area mask 22, thereby the thin film layer for holeinjection 13 is not required to be patterned through lithography or thelike.

At first, as shown in FIG. 3A, as described above, the anode 12 isformed on the substrate 11, and then is patterned. Next, as shown inFIG. 3B, through, for example, high frequency sputtering, by the use ofthe area mask 22 with an aperture 22A corresponding to an area where thethin film layer for hole injection 13 is intended to be formed, the thinfilm layer for hole injection 13 is formed only on desired part, thatis, on the patterned anode 12. The conditions of film formation such asthe sputtering gas and so on are the same as those in the firstembodiment. Then, as in the case of the first embodiment, the insulatinglayer 14, the organic layer 15 and the cathode 16 are formed.

Thus, according to the modification, the thin film layer for holeinjection 13 is formed by the use of the area mask 22, it is notrequired to pattern the thin film layer for hole injection 13 throughlithography or the like. Therefore, even if the anode 12 comprisessilver with high reactivity or an alloy including silver, the anode 12can be prevented from being etched too much during etching to patternthe thin film layer for hole injection 13, or being deteriorated.Thereby, the patterning accuracy of the anode 12 can be improved, andtarget properties of the anode 12 can be obtained. In other words, theorganic electroluminescence device according to the embodiment can beeasily obtained.

[Second Embodiment]

FIG. 4 shows a sectional configuration of an organic electroluminescencedevice according to a second embodiment of the invention. An organicelectroluminescence device 30 is equivalent to the organicelectroluminescence device 10 described in the first embodiment, exceptthat the thin film layer for hole injection 13 is disposed on the anode12 and the insulating layer 14. Therefore, like components are denotedby like numerals as of the first embodiment and will not be furtherexplained.

FIGS. 5A and 5B show a method of manufacturing the organicelectroluminescence device 30 in sequence. At first, as shown in FIG.5A, as in the case of the first embodiment, on the substrate 11, theanode 12 is formed, and then is patterned in a predetermined shapethrough, for example, lithography. Next, as shown in FIG. 5A, as in thecase of the first embodiment, the insulating layer 14 is formed all overthe anode 12 and the substrate 11, and the aperture portion 14A isformed. Next, as shown in FIG. 5B, by the use of an area mask 23 with anaperture 23A corresponding to an area where the thin film layer for holeinjection 13 is intended to be formed, as in the case of the firstembodiment, the thin film layer for hole injection 13 is formed. At thistime, the thin film layer for hole injection 13 is laid on the wholeaperture portion 14A and an edge of the insulating layer 14 around theaperture portion 14A. After that, by the use of the same area mask 23,as in the case of the first embodiment, the organic layer 15 and thecathode 16 are formed.

Thus, according to the embodiment, the thin film layer for holeinjection 13 is formed by the use of the area mask 23, so the embodimentprovides the effects equal to those of the above modification.

Moreover, specific examples of the invention will be described below.

In a manner similar to the first embodiment, the modification of thefirst embodiment and the second embodiment, the organicelectroluminescence devices were manufactured. At that time, the anode12 comprised an alloy including 98% by mass of silver, 1% by mass ofpalladium and 1% by mass of copper, and the thin film layer for holeinjection 13 comprised chromium oxide (III) (Cr₂O₃). When thelight-emitting efficiencies of the organic electroluminescence deviceswere determined at an intensity of 1000 (cd/m²), a voltage of 6.47 (V)and a current of 0.341 (mA), all of them were approximately 11.7 (cd/A).

As a comparative example with respect to the examples, in a mannersimilar to the examples, an organic electroluminescence device wasformed. The organic electroluminescence device was equivalent to theexamples except that like a conventional one, the anode comprisedchromium, and the thin film layer for hole injection was not formed. Thelight-emitting efficiency of the organic electroluminescence device ofthe comparative example determined at an intensity of 1000 (cd/m²), avoltage of 7.16 (V) and a current of 0.69 (mA) was 5.86 (cd/A).

Thus, the examples could obtain approximately twice higherlight-emitting efficiency than that of the comparative example. In otherwords, it turned out that the anode 12 comprising silver could enhancethe reflectance thereof, thereby resulting in improved properties.

The invention is described referring to the embodiments. However, theinvention is not limited to the above embodiment, but is applicable tovarious modifications. For example, the invention is not limited to thematerials and thickness of each layer or the method and conditions offilm formation described in the above embodiments, but any othermaterials and thickness or any other method and conditions of filmformation may be applicable.

In the above embodiments, the configurations of the organicelectroluminescence device are described in detail, but all layers suchas the thin film layer for hole injection 13, the insulating layer 14 orthe transparent electrode 16B may not be necessarily comprised, and anyother layer may be further comprised. In addition, although theinvention can be applied to the case where the semi-transparentelectrode 16A is not comprised, an object of the invention is to enhancethe reflectance of the anode 12, so the case where the semi-transparentelectrode 16A and the anode 12 constitute a resonant portion in aresonator can obtain a higher effect.

As described above, in the organic electroluminescence device accordingto the invention, the anode comprises silver or an alloy includingsilver, so the reflectance of the anode can be enhanced, and a loss oflight absorption by the anode can be reduced. Thereby, the efficiency ofemitting light generated in the luminescent layer can be improved.

Specifically, in the organic electroluminescence device according to theinvention, the anode comprises an alloy including silver, palladium andcopper, so the chemical stability, the processing accuracy and theadhesion of the anode can be improved, thereby resulting in furtherimproved properties.

Moreover, in the organic electroluminescence device according to theinvention, the silver content in the anode is 50% by mass or over, sowhile the reflectance can be sufficiently enhanced, the chemicalstability, the processing accuracy and the adhesion can be improved,thereby resulting in further improved properties.

Further, in the organic electroluminescence device according to theinvention, the thin film layer for hole injection with a higher workfunction than that of the anode is disposed between the anode and theorganic layer, so the efficiency of hole injection into the organiclayer can be enhanced. Further, silver or an alloy including silvercomprised in the anode can be prevented from reacting with oxygen or asulfur content in air, and can mitigate damage to the anode in amanufacturing step after forming the anode.

In a method of manufacturing the organic electroluminescence deviceaccording to the invention, the thin film layer for hole injection isformed in an atmosphere of an inert gas, so even if the anode comprisessilver with higher reactivity or an alloy including silver, the anodecan be prevented from being deteriorated such as oxidation during theformation of the thin film layer for hole injection. Therefore, targetproperties of the anode can be obtained, and thereby the organicelectroluminescence device according to the invention can be easilyobtained.

Moreover, in a method of manufacturing organic electroluminescencedevice according to the invention, the thin film layer for holeinjection is formed by the use of the area mask, so the thin film layerfor hole injection is not required to be patterned through lithographyor the like. Therefore, even if the anode comprises silver with highreactivity or an alloy including silver, the anode can be prevented frombeing etched too much during etching to pattern the thin film layer forhole injection or from being deteriorated. Thereby, while the patterningaccuracy of the anode can be improved, target properties of the anodecan be obtained. In other words, the organic electroluminescence deviceaccording to the invention can be easily obtained.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

The invention claimed is:
 1. An organic electroluminescence device,comprising: an anode which is comprised of a silver alloy, the anodeextending in a horizontal direction, parallel to a substrate andperpendicular to a thickness direction of the anode; a first holeinjection layer provided over the anode, the first hole injection layerextending in the horizontal direction and comprised of ITO (Indium TinOxide); one or more organic layers including at least a luminescentlayer and a second hole injection layer provided over the first holeinjection layer, and the second hole injection layer being comprised ofa material that is different from the first hole injection layer; and acathode provided over the one or more organic layers, wherein lightgenerated in the luminescent layer is emitted from a side of thecathode, and the one or more organic layers have varying thicknesses,and further wherein the cathode extends generally in the horizontaldirection over a central portion of each pixel and the cathode includesa first surface that faces the one or more organic layers and a secondsurface opposite the first surface, the first hole injection layercovering an entire top surface of the anode, and outer sides of theanode and the first hole injection layer are covered by an insulatingmaterial that extends in a first angled upward direction between thehorizontal direction and the thickness direction of the anode andfurther extends upward in a curved leveling off portion, and outerregions of the one or more organic layers and the cathode over the outersides of the anode for each pixel extend upward in the curved levelingoff portion at a second angled upward direction between the horizontaldirection and the first angled upward direction between the horizontaldirection and the thickness direction of the anode, wherein in thecurved leveling off portion over the outer sides of the anode for eachpixel, the first surface of the cathode and the second surface of thecathode both extend upward at the second angled upward direction.
 2. Theorganic electroluminescence device according to claim 1, wherein theanode comprises an alloy including silver, palladium (Pd) and copper(Cu).
 3. The organic electroluminescence device according to claim 1,wherein the anode comprises 50% by mass or over of silver.
 4. A methodof manufacturing an organic electroluminescence device, the organicelectroluminescence device comprising one or more organic layersincluding a luminescent layer between an anode and a cathode andemitting light generated in the luminescent layer from the cathode, themethod comprising the steps of: forming the anode comprising silver overa substrate, the anode extending in a horizontal direction, parallel tothe substrate and perpendicular to a thickness direction of the anode;forming a first hole injection layer extending in the horizontaldirection and comprised of ITO (Indium Tin Oxide), wherein the firsthole injection layer is formed on the anode; forming an organic layerstructure including the luminescent layer and including a second holeinjection layer formed directly over the first hole injection layer; andforming the cathode over the organic layer structure, wherein thecathode extends generally in the horizontal direction over a centralportion of each pixel and the cathode includes a first surface thatfaces the organic layer structure and a second surface opposite thefirst surface, the first hole injection layer covering an entire topsurface of the anode, and outer sides of the anode and the first holeinjection layer are covered by an insulating material that extends in afirst angled upward direction between the horizontal direction and thethickness direction of the anode and further extends upward in a curvedleveling off portion, and outer regions of the one or more organiclayers and the cathode over the outer sides of the anode for each pixelextend upward in the curved leveling off portion at a second angledupward direction between the horizontal direction and the first angledupward direction between the horizontal direction and the thicknessdirection of the anode, wherein in the curved leveling off portion overthe outer sides of the anode for each pixel, the first surface of thecathode and the second surface of the cathode both extend upward at thesecond angled upward direction.
 5. A method of manufacturing an organicelectroluminescence device, the organic electroluminescence devicecomprising one or more organic layers including a luminescent layerbetween an anode and a cathode and emitting light generated in theluminescent layer from the cathode, the method comprising: forming theanode comprising silver over a substrate, the anode extending in ahorizontal direction, parallel to the substrate and perpendicular to athickness direction of the anode; forming a first hole injection layerextending in the horizontal direction and made of ITO (Indium TinOxide), wherein the first hole injection layer is formed on the anode;forming an organic layer structure including the luminescent layer and asecond hole injection layer directly over the first hole injectionlayer; and forming the cathode over the organic layer structure, whereinthe cathode extends generally in the horizontal direction over a centralportion of each pixel and the cathode includes a first surface thatfaces the organic layer structure and a second surface opposite thefirst surface, the first hole injection layer covering an entire topsurface of the anode, and outer sides of the anode and the first holeinjection layer are covered by an insulating material that extends in afirst angled upward direction between the horizontal direction and thethickness direction of the anode and further extends upward in a curvedleveling off portion, and outer regions of the one or more organiclayers and the cathode over the outer sides of the anode for each pixelextend upward in the curved leveling off portion at a second angledupward direction between the horizontal direction and the first angledupward direction between the horizontal direction and the thicknessdirection of the anode, wherein in the curved leveling off portion overthe outer sides of the anode for each pixel, the first surface of thecathode and the second surface of the cathode both extend upward at thesecond angled upward direction.
 6. The organic electroluminescencedevice according to claim 1, wherein the first hole injection layer isformed on the anode by the use of an area mask.
 7. The method ofmanufacturing an organic electroluminescence device according to claim5, wherein the first hole injection layer is formed in an atmosphere ofan inert gas.